Traumatic brain injury (TBI) is a significant public health problem in the US. Yet research is sorely lacking that can generate population-based estimates of TBI in prisons. Estimates of prevalence of TBI in male prisoners from non-population based samples range from 25% to 100%.[1-7] One study of female prisoners estimated a 42% prevalence of TBI.[8] We propose to conduct a population-based retrospective cohort study in South Carolina prisons that will 1) provide interval estimates of prevalence rates of TBI, substance abuse, and violence among representative samples of male and female prisoners;2) quantify the association between history of TBI, substance abuse, and violence and estimate the impact of this association on community integration and recidivism, and 3) investigate the feasibility of conducting routine screening for TBI in prisons by measuring the predictive value positive (PVP) of a new TBI screening tool. This proposed study will identify 292 male prisoners and 292 female prisoners who will participate in in-person interviews shortly before prison release. After entering the community, they will be followed for approximately two years to identify risk factors for recidivism. To help ensure the prevalence estimates, a second cohort of 50 prisoners (25 males and 25 females) will be interviewed. The survey instrument will measure history of TBI, substance abuse, violence, and other potential confounders. The unifying hypothesis guiding the study is that prisoners who report a history of TBI have a higher rate of recidivism mediated by substance abuse and/or violence. This study is intended to provide a clearer understanding of the outcomes of TBI among prisoners and an accurate population-based estimate of the association between TBI, substance abuse, and violence in prisons. This information can assist in providing statewide public health services. Of particular importance is the opportunity this study accords to refine the measures of TBI for correctional settings so they can be useful to inform decision making for corrections and public health. Researchers at the Medical University of South Carolina and Research Triangle Institute will conduct the study activities. Overall study findings will be disseminated through reports and scientific publications to inform corrections and policymakers.